Delay composition for delay electric detonators



2,749,226 v I DELAY COMPOSITION FOR DELAY ELECTRIC DETONATORS Idwal 0. Lewis, Ardrossan, Scotland, assignor to Imperial 2 used. It was, however, not to be expected'that only a narrow range of ratios of red lead to silicon would decrease the deviation of the delay period of the delay element of each delay detonator from a mean delay ice Chemical Industries Limited, a corporation of Great period to such an extent as to permit a series of ventless Britain delay detonators having delay intervals of 25 milliseconds No Drawing. Application April 7, 1952, to be produced. It has now been found by a series of Serial No. 281,029 experiments that by selecting the proportions of red lead Claims priority, application Great Britain June 20, 1951- to silicon so that the red lead is 91*95 per cent by weight 2 C'1 i' CL 5L2) v V and the sil icon fishg fi lper cent 2y weiglit ant;1 by 5300s:

This invention relates to improvements in or relating Lili 3 2i 2 2 :53 1 g g i 5;; to ventless short period delay electric detonators wherean, of it is 3 size less than microns. delay compgsi m th 5 616mm? .conslsts 9 1 l g i g g g fi z tions can be produced which are suitable for use in the gg gg g g i s g g g f f g kinds ]5 production of a series of ventless' delay detonators hav ing delay intervals of milliseconds.

gi g g zzi fig gg i g gg 55652223 52 3 3?: according to the present invention a ventless short zri od delay electric detonator comprising a shell conpenod delay Elect-fie dfatoilator 1S charactensed i that i t 1 ast one detonatin ex losive char a dela the delay composltion 1n 1ts delay element compnses a ammg a e g g 20 mixture of 91-95 per cent by weight of red lead and element conslstmg of a tube i i a fuse composl' 95 per cent by weight of silicon not less than 90 per 21011 In qg g agi gi gg ig i zfig 22 2 53352: cent by weight of said silicon being of particle size less gzg fs 72 p cent by weight of red leadp 12 than 5 microns and all of it of s1ze less than 20 microns.

A delay composition accordin to the invention coml e b (pgratieniilgz vgtielrlgiilttofsililczinisgrtll (indtligzrtcdnltuegtwgi gg 25 P1136; asmlXt'dl'e ofb91-95 Iper gen? by weight of rid legg an per cent y weig t 0 siicon, not ess t an ifiiifiii lily iiiifigfii iihii tfiiiifi?sii tfifi o greater constancy of burning speed 1n ventless delay deto- 32233 5 microns an a of 1t 5126 ess t an nators than those consisting of other proportions of red 30 By varying the lengths of such delay elements gi f i ig h i zgfi i gz i f gi gz g y ig cluded in the detonators the time intervals between the i nd to be too widely scattired about a mean fir :ome Q Sines 5 parallel figng may grgdeterminedi en t ese e ay composltions are ea c into meta g F gi? ,3 i fg inter: tubes of inner diameter 0.130 inch and outer diameter isifiili ii iif elfmliifii' such; 321 338 05 36532- inch in Small each increment being i v 1 liable to occur and this ma pressed at 15 tons per square mob and the so obtained 5 2323: of the Obbct of ugh a f of delay elements loaded into electric detonator assemblies l; detonato to fire a sufl icient nurr ib er of shots in the delay elements W11! have a hnear bl-lmmg Speed of e y bl t d approximately 10 milhseconds per millimetre and the 5132 82521? i i t he gf sg rft in r iiion is t provide a variation of delay periods of such assemblies is so small delay composition which permits the delay element of a 22;; 322322 1 m a 25 mllhsecond Interval delay batch of ventless delay electric detonators having a mean The degree of eness of the silicon used may vary delay period of approximately 25 miliisqconds to be at widely within the limits prescribed above but is preferleast 3 millimetres long and for the dev1at1on of the delay ably Such that at hast 95 er cent b Wei ht is of article period of each detonator from said mean to be sufliciently Size 1955 than 5 microns p y g p to a Series of .vefnfless delay detonators In the following table there is recorded the delay times i g g g g gigii g fi: 3 1 211233; g i f r gg g; in milliseconds for red lead and silicon compositions compositions consisting of mixtures of red lead and silig gi f g gz zfigz g g f gfi gg 5 $2263: con would generally increase with increase in fineness of the silicon used and also that for any particular deance Wlth mventlol? composmons 3 gree of fineness of silicon as the silicon content in- 9 5 to 8, when {lsfid elay elements having an inner creases from Zero the burning speed would increase to diameter of 0.130 inch in commercial ventless delay detoa maximum and thereafter diminish and further that nators- The table also Shows the Proportlons g the ratio of red lead to silicon which gives maximum of the slllconhlhe Percentage dlstrlblltlon burning speed and this maximum burning would diff of the particle size in the silicon, and the lengths of the according to the degree of the fineness of the silicon delay elements.

Composition g ga fig g particle Delay times 111 milliseconds Length of delay Scatter,

element 1. e. dit- N0 Egg Silicon 111mm 35 20-355 10-20 5-10 5 Mean Max. Min. fgfi g max. and

min.

The number of observations as a result of which the mean, maximum, and minimum delay times for each delay element was determined was at least 25. It will be appreciated that in a round of shots to be fired at millisecond intervals, the shots will always fire in the correct order when compositions No. 4 are used but may not fire in the correct order when composition No. 2, 3, 5, 6, 7, or 8 is used. Composition No. 1 would be suitable from the point of variability of delay period but to obtain delay periods of 25, and milliseconds, the delay elements would require to be approximately 1.27, 2.54 and 3.81 millimetres long respectively. Such a series of lengths of delay element would, however, not be convenient for use in manufacturing operations.

What I claim is:

1. A delay composition for a delay element, said composition consisting essentially of a mixture of 91% to 95% by weight of red lead and 9% to 5% by weight of silicon, not less than by weight of said silicon being of particle size less than'S microns and all of it of size less than 20 microns.

2. A delay composition as claimed in claim 1 wherein the silicon is of a degree of fineness such that at least per cent by weight is of particle size less than 5 microns.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,820 Nash Apr. 30, 1935 2,127,603 Jones Aug. 23, 1938 2,586,959 Kerr et al. Feb. 26, 1952 FOREIGN PATENTS 469,168 Canada Nov. 7, 1950 469,169 Canada Nov. 7, 1950 

1. A DELAY COMPOSITION FOR A DELAY ELEMENT, SAID COMPOSITION CONSISTING ESSENTIALLY OF A MIXTURE OF 91% TO 95% BY WEIGHT OF RED LEAD AND 9% TO 5% BY WEIGHT OF SILICON, NOT LESS THAN 90% BY WEIGHT OF SAID SILICON BEING OF PARTICLE SIZE LESS THAN 5 MICRONS AND ALL OF IT OF SIZE LESS THAN 20 MICRONS. 